Efficient preparation of TMSCCl2Br and its use in dichlorocyclopropanation of electron deficient alkenes

Lee, Darren S.; Dur�n-Pe�a, Maria Jesus; Burroughs, Laurence; Woodward, Simon

Abstract

The reaction of excess TMSCl and LiCCl2Br at low temperature is a technically simple high yield route to TMSCCl2Br. The latter is a stable source of the dichlorobromomethide carbanion, which undergoes 1,4-addition with cyclic nitroalkenes and (E)-fumarates leading to dichlorocyclopropanes after bromide explusion. For nitrostyrenes the reaction arrests at the 1,4-addition product. Low temperature NMR studies and DFT calculations suggest the formation of an ‘ate’ species [(nitronate)SiFMe3]- which, upon boil off of TMSF at 10 - 20 °C, yields the cyclopropane. DFT calculations also support the experimental differences between fluoride and acetate as promotors.

Citation

Lee, D. S., Durán-Peña, M. J., Burroughs, L., & Woodward, S. (in press). Efficient preparation of TMSCCl2Br and its use in dichlorocyclopropanation of electron deficient alkenes. Chemistry - A European Journal, 2016(22), https://doi.org/10.1002/chem.201600607

• Journal Article Type: Article
• Acceptance Date: Jan 1, 2016
• Online Publication Date: Apr 26, 2016
• Deposit Date: Apr 27, 2016
• Publicly Available Date: Apr 27, 2016
• Journal: Chemistry - a European Journal
• Print ISSN: 0947-6539
• Electronic ISSN: 1521-3765
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 2016
• Issue: 22
• DOI: https://doi.org/10.1002/chem.201600607
• Keywords: Dichlorocyclopropane, Michael Addition, Cyclopropanation, Conjugate Addition, Cyclopropane
• Public URL: https://nottingham-repository.worktribe.com/output/783692
• Publisher URL: http://onlinelibrary.wiley.com/doi/10.1002/chem.201600607/full
• Additional Information: This is the peer reviewed version of the following article: Lee, D. S., Durán-Peña, M. J., Burroughs, L. and Woodward, S. (2016), Efficient Preparation of TMSCCl2Br and Its Use in Dichlorocyclopropanation of Electron-Deficient Alkenes. Chem. Eur. J.2016, 22., which has been published in final form at doi:10.1002/chem.201600607. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.